Chippy
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| posted on 20/4/06 at 10:01 PM |
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Mark Allison
Mark as stated one thread. What is the best way to work out the angle of the dangle for the sierra upright. I have measured the length ball to ball,
and as near as I can work out it's 8.25 inches, (may be an 1/8th out either way). Regards Chippy
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Syd Bridge
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| posted on 21/4/06 at 08:07 AM |
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What angle are you after? I've got the Ford dwg of the knuckle assy. Angle of the strut line is 13degrees +/-
Syd.
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Mark Allanson
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| posted on 21/4/06 at 08:07 PM |
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Because of having an IQ not much more than my shoe size, made a mistake on my upper wishbones. I made them with additional castor to compensate for
the book error, I used 22mm of setback to give 5°30' of castor, but didn't give it enough thought.
When the car was fully finished, I set up the suspension using the works Hunter system and found the caster was a little less than expected - I just
thought I must have been inaccurate in my fabrication (an ex pro welder fabricator, this was a bit of an admission, but thought little more about
it).
I think I have fully sussed it now (ignoring KPI for now!) for the straight ahead position.
I have used my CAD program to draw a diagram to show what I mean. The upright ball centre dimension has to be the hypotenuse or it would have to
stretch when leant back.
Luckily, my self centring was about ideal for normal driving and for passing the SVA without using the bodges of setting the pressures to 60psi and
having 10° of toe out.
The Sierra builders seem to have a greater problem with the self centring than the cortina builders. I imagine a true castor of 6° should give an
acceptable degree of self centre.
If any maths students could work out a formula for the true setback for a given balljoint centre dimension, I am sure this would help a lot of new
builders. Similarly, if any suspension engineers could verify my thoughts...
 
Rescued attachment True Castor.jpg
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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cymtriks
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| posted on 23/4/06 at 08:12 AM |
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Mark,
"over simplified and incorrect" would be true if you were into measuring everything with a micrometer. In practical terms you won't
notice the error in doing the maths this way.
About 22mm giving about five and a half degrees of castor is fine as far as accuracy is concerned.
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